The present invention relates to the testing of valves, and more particularly, to the acquisition of characteristic environmental data regarding valves in the field.
During the past few years, the nuclear industry has placed increased emphasis on valve operability. One area of concern relates to the effects of adverse environmental factors on valve operability. Additionally, operation of motor-operated valves and stem leakage from all valve types contribute to plant heat and humidity. This can be particularly important in areas accessible by plant personnel, areas containing safety grade process instrumentation and containment. Containment safety analysis may be violated if ambient temperature or humidity exceed the initial conditions assumed in the analysis.
Monitoring temperature and humidity proximate to valves undergoing routine testing provides a means of determining whether valve performance has been affected by a change in these factors. Additionally, an increase in the ambient temperature or humidity immediately adjacent to a valve may indicate excessive stem leakage or motor currents.
The petrochemical industry is required to monitor valve emissions for compliance with the Clean Air Act. Existing technology does not combine the methods of operational valve testing to valve emission testing.
A known approach to valve diagnostics includes operating a valve with a test program while obtaining accurate measurements of, for example, stem thrust or displacement. Such an approach is disclosed in U.S. Pat. No. 5,109,692 (Fitzgerald) which is herein incorporated by reference. By analyzing the relationship of stem thrust, movement, or similar performance variable to the independent energizing variable certain valve behaviors indicative of reliability can be inferred. However, the known approaches do not analyze the relationship between such performance variables and environmental factors to establish valve behaviors indicative of reliability. Additionally, the known approaches do not analyze the relationship between valve emissions and valve performance variables.